Conventionally, a two-phase motor of a solid propellant as shown in FIGS. 12 and 13 has been proposed. The two-phase motor includes a pressure vessel 100 having a rear opening that releases a propellant material, a first pulse explosive grain (a first propellant) 101 arranged in the rear part of the pressure vessel 100, a second pulse explosive grain (a second propellant) 102 arranged in the front part of the pressure vessel 100, a barrier isolator (barrier membrane) 103 for isolating the first pulse explosive grain 101 and the second pulse explosive grain 102 from each other, and a firing device means arranged in the front part of the pressure vessel 100 so that the first pulse explosive grain 101 and the second pulse explosive grain 102 can be fired selectively. The firing device means includes a first pulse firing device (ignition device) 108 arranged close to the first pulse explosive grain 101 and a second pulse firing device arranged close to the second pulse explosive grain 102. The second pulse firing device includes a firing device blocking body 105 in which an annular chamber 104 defining a firing device chamber is arranged and a second firing device explosive grain 106 for firing the second pulse explosive grain. The firing device blocking body 105 is provided with at least one nozzle port 107 for providing a path leading from the annular chamber 104 to the second pulse explosive grain 102 (for example, Patent Document 1).
Also, a two-stage thrust type rocket motor as shown in FIGS. 14 and 15 has been proposed. In this rocket motor, an injection nozzle 113 is disposed at the rear, a first combustion chamber 110 and a second combustion chamber 111 are disposed in the named order from the injection nozzle 113 directly or via a joint 112 in a state of being connected in series. In the first combustion chamber 110, a first propellant 114 having a hollow part penetrating longitudinally is provided, and in the second combustion chamber 111, a second propellant 115 having a hollow part penetrating longitudinally is provided. In the wall surface at a position at which the first propellant 114 is selectively fired, one or more through holes are provided, and in a front-side end part of a first igniting case (ignition device) 119, a first blocking body 121 to which a mechanism for firing a first igniting powder 117 is attached is provided. Also, the first igniting case 119 charged with the first igniting powder therein is arranged on the longitudinal axis line in the first combustion chamber. In the wall surface at a position at which the hollow part wall surface of the second propellant 115 is fired directly, one or more through holes are provided, and in the front-side end part of a second igniting case 120, a second blocking body 122 to which a mechanism for firing the second igniting powder 118 is attached is provided. The second igniting case (ignition device) 120 charged with the second igniting powder 118 therein is disposed in the hollow part of the second propellant 115, and the outer peripheral end part thereof is fixed by the entire of circumference of a rocket motor shell part. A barrier membrane 116 to which the inner peripheral end part of the second igniting case 120 is fixed is provided between the first igniting case 119 and the second igniting case 120 so as to isolate the first propellant 114 and the second propellant 115 from each other (for example, Patent Document 2).    [Patent Document 1] Japanese Patent No. 3231778    [Patent Document 2] Japanese Unexamined Patent Application Publication No. 2005-171970